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Cleanup PPCInstrInfo::optimizeCompareInstr 

Implement suggestions by Bill Schmidt in post-commit review. No functionality
change intended.

llvm-svn: 181338
This commit is contained in:
Hal Finkel 2013-05-07 17:49:55 +00:00
parent e5e416c6de
commit c363245ff2
1 changed files with 10 additions and 14 deletions
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24
llvm/lib/Target/PowerPC/PPCInstrInfo.cpp
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@ -1153,25 +1153,19 @@ bool PPCInstrInfo::optimizeCompareInstr(MachineInstr *CmpInstr,
MachineInstr *UseMI = &*I;
if (UseMI->getOpcode() == PPC::BCC) {
unsigned Pred = UseMI->getOperand(0).getImm();
if (Pred == PPC::PRED_EQ || Pred == PPC::PRED_NE)
continue;
return false;
if (Pred != PPC::PRED_EQ && Pred != PPC::PRED_NE)
return false;
} else if (UseMI->getOpcode() == PPC::ISEL ||
UseMI->getOpcode() == PPC::ISEL8) {
unsigned SubIdx = UseMI->getOperand(3).getSubReg();
if (SubIdx == PPC::sub_eq)
continue;
return false;
if (SubIdx != PPC::sub_eq)
return false;
} else
return false;
}
}
// Get ready to iterate backward from CmpInstr.
MachineBasicBlock::iterator I = CmpInstr, E = MI,
B = CmpInstr->getParent()->begin();
MachineBasicBlock::iterator I = CmpInstr;
// Scan forward to find the first use of the compare.
for (MachineBasicBlock::iterator EL = CmpInstr->getParent()->end();
@ -1188,9 +1182,6 @@ bool PPCInstrInfo::optimizeCompareInstr(MachineInstr *CmpInstr,
break;
}
// Early exit if we're at the beginning of the BB.
if (I == B) return false;
// There are two possible candidates which can be changed to set CR[01].
// One is MI, the other is a SUB instruction.
// For CMPrr(r1,r2), we are looking for SUB(r1,r2) or SUB(r2,r1).
@ -1210,6 +1201,11 @@ bool PPCInstrInfo::optimizeCompareInstr(MachineInstr *CmpInstr,
// Search for Sub.
const TargetRegisterInfo *TRI = &getRegisterInfo();
--I;
// Get ready to iterate backward from CmpInstr.
MachineBasicBlock::iterator E = MI,
B = CmpInstr->getParent()->begin();
for (; I != E && !noSub; --I) {
const MachineInstr &Instr = *I;
unsigned IOpC = Instr.getOpcode();